Explosion-proof refrigerator and freezer



' June 8, 1965 vl.. l. MA1-LESS 3,187,519

EXPLOSION-PRCOF REFRIGERATOR AND FREEZER Filed Allg. 26, 1963 3 Sheets-Sheet 1 T INVENTOR Leonard I. Maf/@5S ATTORNEY June 8, 1955 l.. l. MATLEss 3,187,519

EXPLOSION-PROOF REFRIGERATOR AND FREEZER Filed Aug. 26, 1963 3 Sheets-Sheet 2 5l 4% INVENTOR evnald I. Mafes's BY M 1 .ATTURNEY June 8, 1965 1 l. MATLEss 3,187,519

EXPLOSION-PROOF REFRIGERATOR AND FREEZER Filed Aug. 26, 1963 3 Sheets-Sheet .3

INVENTOR Leonard L Maffe-SS BY Z Z j y t TTRNEY United States Patent() 3,187,519 EXPLSIGN-PROOF REFRIGERATGR AND FREEZER Leonard I. Matless, Cedar Grove, NJ., assigner to Kelmore, Inc., Newark, NJ., a corporation of New Jersey Filed Aug. 26, 1963, Ser. No. 364,348 3 Claims. (Cl. 62-467) This invention relates in general to explosion-proof electrical apparatus, and particularly refrigerators and freezers, especially refrigerators and freezers for industrial use comprising an electrically operated motor-compressor and electrical controls such as relays, thermostats and overload protectors.

A primary object of the invention is to provide apparatus of this character and particularly industrial refrigerators and freezers which shall embody novel and improved features of construction to permit operation of the apparatus in locations in which flammable gases or vapor are, or may be, present in the ambient air without danger of explosion as a result of sparking of the electrical equipment.

Another object of the invention is to provide in an explosion-proof refrigerator or freezer, a novel and irnproved construction and combination of an electrical motor and a refrigerant compressor driven thereby and hermetically sealed in one casing which has an integral steel housing unit or container for the electrical terminals for the motor and compressor, a cover for said housing unit or container to prevent escape of flame from within the container, outlet conduit for electric wires leading from said housing unit` to an explosion-proof steel housing unit or container for the electrical control apparatus for the motor and compressor, a cover for said housing unit or container to prevent escape of flame from within the container, outlet conduits for electrical wires leading from said housing to the integral housing unit on the motor and compressor and toa main control switch, and means for sealing said outlet conduits to prevent escape of flame therefrom into the ambient atmosphere.

Other objects, advantages, and results of the invention will be brought out by the following description in conjunction with the accompanying drawings in which FIGURE l is a front perspective view of one type of refrigerator embodying the invention portions of which are broken away for clearness in illustration;

FIGURE 2 is a top plan thereof;

FIGURE 3 is an enlarged elevational View of the motor-compressor, condenser coil and electrical outlet conduits taken approximately from the plane of the line 3-3 of FIGURE 2;

FIGURE Ltf-A is a further enlarged perspective view of the motor-compressor and a portion of the electrical conduit leading therefrom, with the major portion of the cover of the housing unit or container for the electrical terminals broken away.

FIGURE 4-B is a further enlarged perspective view of the housing unit or container for the electrical controls, and portions of the electrical conduits leading therefrom, with the major portion of the cover of the housing unit broken away.

FIGURE 5 is an enlarged transverse vertical sectional view through one of the conduit sealing devices approximately on the plane of the line 5 5 of FIGURE 3j FIGURE 6 is a fragmentary vertical longitudinal sectional view approximately on the plane of the line 6 6 of FIGURE 5;

FIGURE 7 is a wiring diagram of the electrical apparatus; and

FIGURE 8 is a front perspective View of the reducing 3,187,519 Patented June 8, 1965 ICC bushing 32 and brass plug 33 assembly used to explosion-i proof the `outlet from the control housing W for the capillary tube N.

For the purpose of illustrating the principles of the invention, it has been shown as embodied in one type of refrigerator, but it will be understood by those skilled in the art that the invention is equally susceptible to use with other types of electrical refrigerators, freezers and apparatus. i

As shown, the refrigerator includes the usual main casing or housing A having one or more refrigerating compartments normally closed by a hinged door B and above which is located an evaporator unit C of generally known construction which is connected in the usual way with a condenser coil D mounted on the back of the housing A and connected to the compressor of a motor-compressor unit E that is mounted on a support F which may be set on the floor and is preferably connected to and carried by the rigid metal frame G on which the condenser D is mounted.

Hot discharge gas from compressor E is pumped through the copper tubing 3S which is imbedded in the insulation around the periphery of the opening to the low temperature compartment in cabinet A, FIG. l. This raises the temperature of the exterior of the cabinet at this point sufficiently to prevent moisture condensation around the door. This new and novel method is used in lieu of the normal manner of heating the same areas with electric strip heaters which cannot be used in explosion proof construction.

The compressor is driven by an electrical motor in the usual way and has its outlet H connected to the upper end of the condenser D which is in the form of a zigzag coil of tubing and the other end of which is connected by a tube K to the inlet of the evaporator C which is of known construction land only schematically illustrated and the outlet of which is connected by a tube L to the suction side or inlet of the compressor as indicated at M.

A sensory capillary tube N connects the compressor in known manner to a sensing unit for control of the temperature, and the motor-compressor unit has an integral housing or container O for known electrical terminals. This housing is connected to an explosionproof housing W for known electrical control apparatus generally designated P which usually Aincludes overload protectors, relays and thermostats. The capillary tube N is soldered into the brass plug 33 which is in -turn press tit in reducing bushing 32 and further secured with set screw v34. This assembly is screwed into boss on housing W and engages at least 5 yfull threads. The O D. of the brass plug and the I D. of the reducing bushing are machined to such close tolerances that heat or flame arising from combustion or explosi-on of ammable gases within the housing W and escaping between the plug and the bushing will be so restricted and cooled as -to eliminate the possibility of communicating such heat or flame to the surrounding exterior atmosphere, in such a manner as to ignite flammable :gases in lthe ambient atmosphere. While the electrical `apparatus per se forms no part of the invention, to facilitate understanding of the invention, a 'wiring diagram is shown in FIGURE 7 and includes the motor-compressor terminals 1 and 2 that are connected to opposite terminals of a relay generally designated 3, the solenoid of which is connected to one terminal of a control unit 4 the other terminal Iof which is connected to one terminal of the line switch 5 whose other terminal is connected through an overload protector 6 to the third terminal 7 of the motor-compressor. The housing or container O has a section 8 that is preferably integral rwith the casing of the motorcompressor :and which has a screwed cover 10 which engages at least full threads -on housing O. The housing or container W has a screwed cover X which engages at least 5 full threads on the housing W so that heat or flame :arising from combustion or explosion of flammable gases within the housing and escaping between the threads onV the Vhousing Iand on the cover will be so restricted and cooled as -to eliminate the possibility -of communicating such heat /orflaineito the surrounding .exterior atmosphere, in such a manner as yto ignite `flammable gases in the ambient atmosphere. Y

Wires Al2 for connecting the motor-compressor unit to the .control apparatus P and'in an electricalcircuit with the line extend through an outlet bushing 13 that is threaded into the wallof the housing and said wires `are threaded through a conduit generally designated Q to an explosion-proof main switch R5 that is shown as mounted o n a bracket S which is secured to the frame G on which the `condenser coil D is mounted.

ln addition to the sealing of the control apparatus in the housings O and W, the invention contemplates the explosion-proof sealing kof the wires l2 in the conduit sothat ignition of `ilarnmable gases or vapors in the vicinity ofthe refrigerator, such as might `occur from sparks in the conduit, will be prevented. For this purpose a sealing device V forms a portion -of t-he conduit Q :and isinterposed between and has a fluid-tight conknection with the outlet fitting -13 and -an explosion-proof llexiblemetal pipe or hose U and another sealing device V explosion-proof fluid-tight connections with said ilexible. pipe #U .and the explosion-proof switch R.

YMore kparticularly ydescribing the sealing devices, the device T includes a hollow main or body section 14 having an lopening .15 in 4one side thereofwhich is normally closed by a screw plug V16 that has anfopening 17 therethrough and through yan .extension 13 thereof for insertion of a semi-fluid or plastic; sealing compound, the opening -17 normally being closed by a plug 19. Tubular extensions :20 project integrally from opposite sides of the body 14 `in .alignment with each other so that the wires rlZmay be threaded through the device and through anipple 20', into .housing W :and through an elbow 2l and a .union .el-bow yZ2 .into the housing O, the joints between .the nipple, elbow, coupling, and housings being fluidftight -or explosion-proof, with engagement of at least tive rfull threads. y

While the manner of sealing the wires in the device may be varied, preferably a thin walled bushing 23 is inserted into each kof ktheextensions 20 and lhas an interior` circumferential groove 2d into which suitable packing .mater-ial, such as asbestos tibers, may be pressed through the opening Al5 of the housing ywhen the plug is removed from said opening and after the wires have ybeen threaded through the device. The plug 16 is then screwed into the body and a suitable plastic sealing compound 25 is inserted throughthe opening 17 into the hollow body as shown in FIGURE 5.

The sealing devices V and V have a straight tubular body-26 and an upwardly inclined tubular branch 27 that is normally closed by a Vscrew plug 2,8; and one end of the housing .26 is connected to Ithe hose U through a nipple .29 to union coupling 29 while theother end of the `4tubular .body 26 is connected by a nipple 29 to the casing of .the explosion-proof switch R.V The wires passing 'from the sealing device V through the hose U also pass through thetubular body 26 and are connected to :the terminals of the switch R; and these wires are sealed in the sealing devices V and V .in aboutV the same mannersin .which .they Iare sealed in the sealing device T, the sealing compound kbeing `inserted through ,the branch 27.

With this construction and combination of parts it will be-seen that `the apparatus may be located and oper-ated 'in locations yin which flammable gases or vapors are .present in the ambient air without danger of explosion as a result of flame or sparks that may :be produced in the electrical parts. The invention provides novel explosion-proof electrical controls and wiring that are simple and relatively inexpensive both in manufacture and installation. Any names Ior sparks that might originate in the housings O and W will be restricted and cooled so as to eliminate the possibility of passage of the heat or fiarne to the surrounding exterior atmosphere and will also be prevented by the lsealing device V from entering the conduit Q. Sealing devices V and V seal Ioff the hose U from the appara-tus housing W and from the main line switch R, and the sealingdevice T seals off the housing O from the apparatus housing W.

While the construction of the refrigerator itself is relatively immaterial, it will be understood rthat generally the frame G will be channel shaped in cross section and have the Vcondenser coil mounted thereon and the frame willbe preferably attachedto l.the exterior of the rear wall of the refrigerator housing A, as .by bolts or screws passing through openings 3i in the kframe into the rear Wall of the housing to provide a sha-ft for the passage of cooling airaround the condenser coil as best shown in FIGURE 2.

It will also be understood that theevaporator C is mounted within the insulated-housing or shell A and that said housing .or shell does not contain any wiring, lights, switches Ior lany other devices which could produce a spark or name.

While the now preferred embodiment of the invention has been illustrated and described, it will be understood that this is primarily for the purpose of illustrating the principles of the `invention and that modifications and changes may be made in the details of construction and the invention may be embodied in other paratus, all within the spirit and scope of the invention. For example, the number of the sealing .devices T and V may be varied to suit different conditions, some apparatus requiring one such sealing device' and other apparatus requiring two or more sealing devices.

What I claim is:

l. An explosion-,proof refrigerator, the combination with a motor-compressor unit, including an electric motor and a refrigerant compressor vdriven thereby hermetically sealed in one casing`,1of a housing kintegral with said casing and having therein electrical motor terminals for said unit, said integral housing having a threaded opening anda cover removably secured thereto with a flame-proof join-t, an explosion-proof control housing having therein electrical control apparatusfor said motor-compressor unit, said control housing having a threaded opening and acover removably secured theretowitli a flame-proof joint, a sensory capillary tube, a metal plug through which said capillary tube passes with ailuid-tight connection, a reducing bushing screwed into Ysaid control housing and in which said Ametal plug extends with a press iit to such close tolerances asto provide a flame-proof and explosionproof joint, one end of the sensory tube being connected to a thermostat in said control apparatus andlthe other end being adapted to be lpositioned in a refrigerated area, aneXplosion-proof mainswitch, wires some of which electrically connect said motor terminals to said control apparatus and others of which connect said control apparatus to said switch, Vand explosion-proof conduits for said wires between said integral housing and said control housing and between said control housing and said switch having explosion-proof connections with said control housing and with said integral housing and with said switch and including Yat least ,two sealing devices one between saidintegral housing and said control housing and another between said control housing and said swi-tch, each device including a hollow body through which said wires are threaded and y.in which isa plastic sealing compound that seals the wires in said body and prevents passage offiarne and fluidinthe conduits from either` side of said body to the other.

2. lnpan explosion-proof refrigerator asrdened in claim types of ap- 1, said explosion-proof connections between said conduit and said integral and control housings and between said conduit and said switch are screw threaded with engagement of at least five full threads.

3. In an explosion-proof refrigerator as defined in claim 1, the explosion-proof conduit between the control housing and the switch comprising a nipple having a screw-threaded connection with the hollow body of :the second-mentioned sealing device and having a screwthreaded connection at its other end with said switch, a second nipple screw-threaded into said hollow body of the second-mentioned sealing device, a exible coupling hose, means having screw-threaded connections with both said second nipple and said hose for connecting them, and the addition of a third sealing device including a hollow body having a screw-threaded connection with said control housing, and means having screw-threaded connections with both the hollow body of said third sealing device and said hose for connecting them, said wires extending from said control apparatus to said switch through said conduit, and the hollow body of the third sealing device having a sealing compound therein that seals the wires in said body and seals the conduit against passage of flame and iluid in the conduit from either side of said body to the other.

References Cited by the Examiner UNITED STATES PATENTS 2,537,314 1/51 Mortensen 62-273 X 2,574,882 11/51 McDowell et a1. 174-152 2,744,202 5/ 5 6 Horvath et al. 174-151 3,003,683 lO/61 Manning et a1 174-20 X ROBERT A. OLEARY, Primary Examiner. 

1. AN EXPLOSION-PROOF REFRIGERATOR, THE COMBINATION WITH A MOTOR-COMPRESSOR UNIT, INCLUDING AN ELECTRIC MOTOR AND A REFRIGERANT COMPRESSOR DRIVEN THEREBY HERMETICALLY SEALED IN ONE CASING, OF A HOUSING INTEGRAL WITH SAID CASING AND HAVING THEREIN ELECTRICAL MOTOR TERMINALS FOR SAID UNIT, SAID INTEGRAL HOUSING HAVING A THREADED OPENING AND A COVER REMOVABLY SECURED THERETO WITH A FLAME-PROOF JOINT, AN EXPLOSION-PROOF CONTROL HOUSING HAVING THEREIN ELECTRICAL CONTROL APPARATUS FOR SAID MOTOR-COMPRESSOR UNIT, SAID CONTROL HOUSING HAVING A THREADED OPENING AND A COVER REMOVABLY SECURED THERETO WITH A FLAME-PROOF JOINT, A SENSORY CAPILLARY TUBE, A METAL PLUG THROUGH WHICH SAID CAPILLARY TUBE PASSES WITH A FLUID-TIGHT CONNECTION, A REDUCING BUSHING SCREWED INTO SAID CONTROL HOUSING AND IN WHICH SAID METAL PLUG EXTENDS WITH A PRESS FIT TO SUCH CLOSE TOLERANCES AS TO PROVIDE A FLAME-PROOF AND EXPLOSION PROOF JOINT, ONE END OF THE SENSORY TUBE BEING CONNECTED TO THE THERMOSTAT IN SAID CONTROL APPARATUS AND THE OTHER END BEING ADAPTED TO BE POSITIONED IN A REFRIGERATED AREA, AN EXPLOSION-PROOF MAIN SWITCH, WIRES SOME OF WHICH ELECTRICALLY CONNECT SAID MOTOR TERMINALS TO SAID CONTROL APPARATUS AND OTHERS OF WHICH CONNECT SAID CONTROL APPARATUS TO SAID SWITCH, AND EXPLOSION-PROOF CONDUITS FOR SAID WIRES BETWEEN SAID INTEGRAL HOUSING AND SAID CONTROL HOUSING AND BETWEEN SAID CONTROL HOUSING AND SAID SWITCH 